The decision closes the door, for now, on a probe that had hung over Powell after his tenure leading the Federal Reserve. The investigation concerned cost overruns related to the central bank's building renovation.
According to Bloomberg News, which first reported the development, Blanche said the department was not reopening the case. But he left open the possibility of further review of the project's oversight, and of action if evidence of wrongdoing came to light.
Powell, who led the Fed until Kevin Warsh took over, had been investigated over the renovation costs. The department's decision means he will not face criminal charges in connection with the matter at this time.